How to access Debug and Launch Settings if greyed out? - c++

Question

I'm trying to edit my launch settings for a CMake project in Visual Studio, but the option is greyed out. I can manually open launch.vs.json file, but the settings there won't behave.
Probably the greying out and the fact that the settings won't behave are linked.
I am running the x64-Debug configuration.
This is how launch.vs.json looks like for me:
{
"version": "0.2.1",
"defaults": {},
"configurations": [
{
"type": "default",
"project": "CMakeLists.txt",
"name": "CMakeLists.txt",
"args": [
"first-argument"
],
"currentDir": "C:\\repos\\myproject"
}
]
}
Since the type of the configuration is "default", I would assume it applies for any configuration that isn't configured. But it doesn't because my "first-argument" is not read.
int main(int argc, char* argv[])
{
if (argc>1)
{
cout << argv[1];
exit(EXIT_SUCCESS);
}
else
{
exit(EXIT_FAILURE);
}
}
The above yields failure.
How to properly configure the debug parameters and how to ungrey Debug and Launch settings?

Answer 1

The Configure CMake debugging sessions documentation says that
If you don't have a debug target selected, this option is grayed out.
Running the x64-debug configuration sounds like the option shouldn't be greyed out, but it still is because you're debugging the Current Document as a target, which Visual Studio doesn't consider a real target. This means that Current Document is neither a Debug, nor a Release target, so the option is greyed out, even if you run it with the configuration named x64-Debug.
Real targets have a drop down menu on the right, usually with a single item mentioning the type of the selected target.
This means you need to select a real target, which should be something like myproject.exe for you.
According to the launch.vs.json schema reference (C++) documentation page, "type": "default" refers to whether the project is a library or an executable, and default just means that it's an executable. It has nothing to it being the default configuration.
The relevant setting to link debug configurations to targets is projectTarget, which is not set in your case. It could be that it used to be that the default would make this configuration available for all targets, including the virtual Current Document, but this would have been an undocumented feature that was unexpectedly deprecated without notice in a new Visual Studio release. This could explain, why it used to work, but it doesn't anymore.
According to the launch.vs.json schema:
projectTarget must exist already and match the name in the Debug Target dropdown.
The easiest way to create a real launch and debug configuration is to
delete your launch configuration,
select a real target, such as "myproject.exe", and make sure it says Debug on the drop-down menu on the right.
Go to Debug -> Debug and Launch settings for myproject.exe, which should open launch.vs.json with a valid configuration, now fill in the "args" parameter as you wish.
Your final configuration should probably look like similar to this:
{
"version": "0.2.1",
"defaults": {},
"configurations": [
{
"type": "default",
"project": "CMakeLists.txt",
"projectTarget": "myproject.exe (myproject\\myproject.exe)",
"name": "myproject.exe (myproject\\myproject.exe)",
"args": [
"first-argument"
],
"currentDir": "C:\\repos\\myproject"
}
]
}
I hope this will serve me as a good reminder to spend more time on documentations and less time messing around.

Answer 2

The answer for me was that somehow the "Startup Item" magically got deselected, so there was no context for Debug and Launch Settings.
In Solution Explorer, right-click on the executable that is the target of the Debug Launch -- "myproject (executable)" in this case -- and select Set as Startup Item.
Now, whenever this executable is selected in the Solution Explorer, the option "Debug and Launch Settings for myproject" appear in the Debug dropdown menu.